Method of preventing corrosion of metallic petroleum refining apparatus and composition therefor



S ttlt Patented Nov. 17, 1959 METHOD OF PREVENTING CORROSEON OF ME- TALLIC PETROLEUM REFINING APPARATUS AND COMPOSITION THEREFOR Charles 0. Hoover, Corpus Christi, Tex.

No Drawing. Application July 27, 1955 Serial No. 524,813

22 Claims. (Cl. 208-257) This invention relates to a process for preventing or inhibiting destructive corrosion of metallic petroleum refining equipment caused by corrosive constituents normally contained in many crude petroleums, and to a chemical composition for use in such process.

Most crude petroleums contain numerous naturally occurring constituents and impurities which will cause severe corrosion of the metals from which conventional petroleum refining equipment is constructed. These corrosive or corrosion-causing materials include acidic materials such as hydrogen sulfide, carbon dioxide, and organic acids. Oxygen, which is often present usually by reason of air absorbed in or admixed with the petroleum, is a particularly corrosive agent, especially at the temperatures to which the crude petroleum and its fractions are subjected during heating and distillation. Salt water or brine, which is commonly produced with, and is usually present in, most crude oils, and salts, such as magnesium chloride, contained in the brine, will hydrolyze or otherwise decompose during the heating and distillation processes to form hydrochloric acid, which, in the presence of water vapor and liquid water in the condensers, will cause severe metallic corrosion. Also, mercaptans and other sulfur compounds normally present in varying amounts in different types of crude petroleums will decompose during heating and distillation to form corrosive compounds including particularly hydrogen sulfide.

Many types of treatment have been employed in attempts to combat such corrosion in petroleum refining systems. None has proven particularly successful in efiectively preventing corrosion although some have reduced the rate of the corrosive action to a point where replacement of equipment may be kept within tolerable limits, although sooner or later major parts of the equipment must be replaced. In the case of high sulfur crude oils, such as Mexican crudes, a high rate of equipment replacement has been accepted as a normal operating condition irrespective of the corrosion-combating processes which have heretofore been employed to protect such equipment.

It is a primary object of the present invention to provide a. process for preventing corrosion in petroleum refining equipment or the like by subjecting crude petroleum or its fractions in either liquid or vapor phase with a chemical treating agent which is low in cost, easy to apply and extremely effective in its corrosion-preventing characteristics.

An important object of this invention is to provide a process. for combating corrosion of petroleum refining equipment by adding to crude petroleum as it enters the refining system a chemical treating agent adapted to effectively neutralize or inhibit the various corrosioncausing constituents in the crude petroleum.

Another object of the invention is to provide chemical compositions suitable for use in the above processes and methods of preparing such. compositions.

Briefly stated, the present invention comprises a chemical composition for inhibiting corrosion of metallic pctroleum refining apparatus caused by corrosive constituents contained in the petroleum processed in said apparatus comprising a concentrate of an ammoniacal copper carbonate complex and methods of utilizing the same.

The referred-to concentrate may be dissolved in an aqueous alkaline medium to form a final treating solution which is added to the petroleum or to a vaporized portion thereof.

The concentrate may, as will subsequently appear, be prepared by several methods but regardless of the method of its preparation, its active ingredients are the same and its method of use is the same.

It is found that the ammoniacal copper carbonate complex when added to crude petroleum in the liquid phase and at ordinary atmospheric temperatures reacts almost instantaneously with the numerous corrosive agents which may be present in the crude petroleum to form alkali salts and copper compounds which will be stable at the ordinary distillation temperature and will accumulate in.

the unvaporized residues, thereby leaving the vaporized hydrocarbons completely free of corrosive constituents which might otherwise corrode the distillation, cooling and condensing equipment.

The copper ion in the complex may be in reduced or cuprous state or it may be in the oxidized or cupric state. In either state the complex will effectively neutralize the acidic corrosive substances. However, where oxygen is present in the petroleum the copper ion should be in the reduced or cuprous state when introduced into the process. The ammoniacal copper complex may be readily maintained in the reduced state by storing it in contact with metallic copper and maintaining a slight excess of ammonia in the solution.

The treating composition may be prepared in various ways which will be Well understood by those skilled in this art. As it is ordinarily desirable to employ a solution having a relatively high copper concentration, methods of preparation should be employed which will result in the desired high concentration of copper in the treating solution. Concentrated aqueous ammonia dissolves metallic copper quite slowly in the presence of oxygen. Liquid ammonia will dissolve copper hydroxide and copper carbonate to a concentration of 4 to 5 percent by weight of copper. Aqueous ammonium carbonate solution in the presence of excess ammonia will readily dissolve copper hydroxide and copper carbonate to a concentration of 12 to 14 percent by weight of copper.

In most instances the preferred treating compound will comprise ammoniacal-copper-carbonate complex dissolved in sodium carbonate solution and this mixture is referred to as the final treating solution. The concentrate is usually a liquid product but a mixture of dry materials may be prepared which, when dissolved in water, forms the desired final treating solution.

One example of the composition of the treating agent made up in liquid form is as follows:

Parts by weight Copper (ic) carbonate 34 Water 70 Carbon dioxide 10 Ammonia 24 stirring. The. resulting solution will be a copper-ammonium-carbonate complex which will contain from 13.5 to 14.0% of copper. This complex is then mixed with an alkali usually at the time of use, to form an alkaline solution which becomes the final treating solution. Preferably, it is mixed with sodium carbonate solution, preferably about 13 B., to form a complex ammoniacal sodium-ammonium copper carbonate solution in which the copper ion may be in either the reduced or oxidized state at the time of use.

The treating compound in accordance with this invention may be prepared in the dry state by mixing ammonium bicarbonate, copper carbonate, and soda ash to form a dry mixture of the desired composition. This dry material may then be dissolved in water at the time of use to form the ammoniacal sodium-ammonium copper-carbonate solution (i.e., the final treating solution).

A typical admixture in the dry state is as follows:

Percent by weight Ammonium bicarbonate 5 Copper carbonate /2 Sodium carbonate 94 /2 Ammonium carbonate may be substituted for ammonium. bicarbonate in amounts which will provide the corresponding Weight proportion of the ammonium ion.

The proportions of ammoniacal copper carbonate to alkali solution are variable, the relative proportions being determined primarily by the nature and concentration in the petroleum of corrosive constituents and impurities to be reacted with the reagent.

In preparing the copper-ammonium-carbonate complex in the form of a liquid concentrate, it will be evident that instead of dissolving the ammonia and carbon dioxide gases in water, functional equivalents corresponding to the reaction products of these gases in water, for example, ammonium carbonate or ammonium bicarbonate, may be dissolved in water and, in the presence of excess ammonia, may be substituted for the water solution of the gases with equal eifectiveness for dissolving the coppercontaining salts to produce the copper-ammonium-carbonate complexes containing the desired proportion of copper. Following is an example of a concentrate of an ammoniacal copper carbonate complex made in this In this example the two salts are dissolved in aqueous ammonia solution and provide a complex containing about by weight of copper.

Following are several examples illustrative of the varying compositions which may be employed on crude petroleums containing varying quantities of corrosive constituents and impurities which are removed or neutralized by the compositions in accordance with this invention.

Example 1 Crude oil A-which upon distillation prior to treatment produced overhead products containing corrosive materials as follows:

Water: pH3.2 (acidic) Gasoline: H 8 and R.SHl mg./ 100 ml.; acidval.-0.00 Kerosene: H Snone; R.SH3 mg./100 ml.; acid val.- 0.017 Ragggpil: H S-none; R.SH3 mg./100 ml.; acid val.-

To this crude oil there was added 0.04% by volume of the compound in accordance with the present invention having the following composition (percent by weight):

The overhead recovered from distillation of the treated crude contained no corrosive materials as shown below:

Water: pH-7.2 (neutral) Gasoline: H 8, R.SHnone; acid value0 Kerosene: H 5, R.SHnone; acid value--0 Range oil: H 8, R.SHnone; acid value0 Example 2 Crude oil B-overhead products before treatment:

Water: pH1.9 (acidic) Gasoline: H R.SH3 mg./ ml.; acid val.-0.00 Kerosene: H' Snone; R.SH4 mg./ 100 ml.; acid val Range oil: H S-none; R.SI-I-5 mg./1'00 ml.; acid val.-

To this crude oil was added 0.113% by volume of the compound in accordance with the present invention having the following composition (percent by weight):

Copper (as metal) (Cu) Ammonia (NH 0.148 Carbon dioxide (CO 0.108 Sodium carbonate (Na CO 10.000 Water (H O) 89.619

Total 100.000

The overhead recovered from distillation of the treated crude contained no corrosive materials, as shown below:

Water: pH7.0 (neutral) Gasoline: H S, R.SHnone; acid val.--0

Kerosene: H 8, R.SHnone; acid val.0

Range oil: H S, R.SHI mg/ 100 ml acid val.0

A slight increase in the copper content of the treating solution would have completely removed the mercaptans.

Example 3 Crude oil C-overhead products before treatment: Water: pH1.1 (acidic) Gasoline: H 8, R.SH28 mg./ 100 ml.; acid val-0.002 Kerosene: H Snone; R.SH33 mg./ 100 ml.; acid va1.-0.08 Range oil-H Snone; R.SH47 mg./ 100 ml.; acid To this crude all was added 0.113% by volume of the compound in accordance with the present invention having the following composition (percent by weight):

Copper (as metal) (Cu) 1.144 Ammonia (NH 1.358 Carbon dioxide (CO 0.990 Sodium carbonate (Na- CO 8.34 Water (H O) 88.168

Total 100.000

'The overhead products recovered from the treated crude contained no corrosive materials as shown by the following analyses:

Water: pH7.4 (neutral) Gasoline: H S, R.SHnone; acid val.0 Kerosene: H 8, R.SHnone; acid val.-0 Range oil: H 5, R.SHnone; acid val.-0

The treating compositions will ordinarily be injected directly into the crude oil entering the distillation system where it may be thoroughly admixed therewith. In most cases about 2 gallons of treating solution per 1000 barrels of crude oil will provide satisfactory treatment, although it will be understood that this volume ratio may be varied widely. The reactions with the corrosive constituents appear to take place substantially instantaneously at atmospheric temperatures and it is found that the distillation, fractionation, condensing and cooling equipment will be remarkably free of any form of corrosion or of deposits of reaction products such as frequently are found to result from the use of other treating agents.

The reagent may be contacted with the petroleum in the vapor phase, for example, by pumping it onto bubble trays or other liquid-vapor contacting surfaces present in" conventional petroleum distillation and fractionation equipment. Ordinarily, however, it will be found preferable to treat the whole crude oil as it enters the distillation system.

As indicated previously the quantity of the treating agent required will ordinarily be quite small, usually only a very small fraction of 1% by volume of the petroleum. Also, the proportion of the ammoniacal copper carbonate complex in the treating agent is ordinarily quite small, ranging from a fraction of one percent to about 5.0 percent by weight of the treating agent.

As noted previously, by employing a composition as herein described wherein the copper ion is in the reduced or ous state, any free oxygen will be readily absorbed, thereby eliminating one of the more serious corrosive and gum-forming agents from the distillation system.

If the petroleum is substantially free of free oxygen, the copper in the treating composition may be in the oxidized or ic state, in which it will inhibit or neutralize the other corrosive constituents which may be present.

The composition herein described is also found to be exceptionally eilective in removing acidic, gum-forming and other similarly undesirable constituents or compounds present in many distillate fractions produced from crude oil and from the cracked products thereof. Such fractions are preferably treated by contacting them while in the vapor phase with a composition in accordance with the present invention.

From the foregoing, it will be apparent that the present invention provides a highly useful method and product for preventing or reducing metallic corrosion in petroleum refining equipment.

What I claim and desire to secure by Letters Patent is:

1. The method of inhibiting corrosion in metallic petroleum distillation apparatus which comprises admixing an ammoniacal copper carbonate complex with the petroleum being distilled in said apparatus.

2. The method of inhibiting corrosion in metallic petroleum distillation apparatus which comprises admixing an ammoniacal cuprous carbonate complex with the petroleum being distilled in said apparatus.

3. The method of inhibiting corrosion in metallic petroleum distillation apparatus which comprises admixing an ammoniacal cupric carbonate complex with the pe-' troleum being distilled in said apparatus.

4. The method of inhibiting corrosion in metallic petroleum distillation apparatus which comprises admixing with petroleum being distilled in said apparatus an aqueous alkaline solution of an ammoniacal copper carbonate complex.

5. The method according to claim 4 wherein the aqueous alkaline solution comprises a Water solution of sodium carbonate.

6. The method according to claim 4 wherein the aqueous alkaline solution comprises a water solution of sodium carbonate and wherein the copper in said carbonate complex is in the reduced state.

7. The method according to claim 4 wherein the quan- 6 tity of aqueous alkaline solution of the ammoniacal copper carbonate complex added to the petroleum is substantially less than one percent of the volume of said petroleum.

8. The method of protecting metallic petroleum distillation apparatus from corrosion by corrosive constituents contained in crude petroleum processed in such apparatus which comprises admixing with crude petroleum in liquid phase as it enters said apparatus an aqueous alkaline solution of an ammoniacal copper carbonate complex, and subjecting the resulting admixture to distillation in said apparatus.

9. A method according to claim 8 wherein the quantity of said solution is substantially less than 1% by volume of the crude petroleum.

10. A method according to claim 8 wherein the copper ion in said complex is in the reduced state.

11. A chemical composition for inhibiting corrosion of metallic petroleum refining apparatus by corrosive constituents contained in the petroleum processed in said apparatus, consisting of an aqueous solution of ammoniacal copper carbonate complex and sodium carbonate.

12. A chemical composition according to claim 11 wherein the copper in the ammoniacal copper carbonate complex is in the reduced or ous state.

13. A chemical composition according to claim 11 wherein the quantity of said ammoniacal copper carbonate complex in said solution ranges from less than 1 percent to about 5 percent by weight of said composition.

14. The method of removing corrosive and gum-forming constituents from petroleum fractions which comprises vaporizing a petroleum fraction and contacting said fraction in the vapor phase with an aqueous alkaline solution of an ammoniacal copper carbonate complex.

15. The method of protecting metallic petroleum distillation apparatus from corrosion by corrosive constituents contained in crude petroleum processed in such apparatus which comprises admixing with crude petroleum in liquid phase as it enters said apparatus a composition consisting of an aqueous solution of an ammoniacal copper carbonate complex and sodium carbonate, and subjecting the resulting admixture to distilla tion in said apparatus.

16. A method according to claim 15 wherein the quantity of said composition added to the crude petroleum is less than one percent by volume of said crude petroleum.

17. A chemical composition for inhibiting corrosion of metallic petroleum distillation apparatus by corrosive constituents contained in the petroleum processed in said apparatus, comprising a liquid composition consisting of copper carbonate, water, carbon dioxide and ammonia in proportions such as to provide a concentration therein of from about 13.5 to 14.0 percent of copper.

18. A chemical composition for inhibiting corrosion of metallic petroleum distillation apparatus by corrosive constituents contained in the petroleum processed in said apparatus, comprising, a liquid composition consisting of aqueous sodium carbonate in which is dissolved from less than 1% to about 5.0% by weight of an ammoniacalcopper-carbonate complex, said complex containing from about 13.5 to about 14.0 percent by weight of copper.

19. A chemical composition for inhibiting corrosion of metallic petroleum distillation apparatus by corrosive constituents contained in the petroleum processed in said apparatus, comprising, a dry base admixture to be dissolved in water, said dry base consisting of:

Percent by Weight Ammonium bicarbonate 5 Copper carbonate /2 Sodium carbonate 94 /2 20. A chemical composition for inhibiting corrosion of metallic petroleum distillation apparatus by corrosive constituents contained in the petroleum processed in said apparatus, comprising a liquid composition consisting of copper carbonate, ammonia, water, and a member of the class consisting of ammonium carbonate and ammonium bicarbonate, in proportions such as to provide a concentration of from about 4 percent to about 14 percent by Weight of copper.

21. A chemical composition for inhibiting corrosion of metallic petroleum distillation apparatus by corrosive constituents contained in the petroleum processed in said apparatus, comprising a liquid composition consisting of ammonia, water, a member of the class consisting of copper carbonate and copper hydroxide, and a member of the class consisting of ammonium carbonate and ammonium bicarbonate, in proportions such as to provide a concentration of from about 4 percent to about 14 percent by weight of copper.

22 A chemical composition for inhibiting corrosion of metallic petroleum distillation apparatus by corrosive constituents contained in the petroleum processed in said apparatus, comprising a liquid composition consisting of aqueous sodium carbonate in which is dissolved from less than 1% to about 5% by Weight of an ammoniacedcopper-carbonate complex, said complex comprising a liquid composition consisting of ammonia, water, a mem ber of the class consisting of copper carbonate and copper hydroxide, and a member of the class consisting of ammonium carbonate and ammonium bicarbonate, in proportions such as to provide a concentration of from about 4 percent to about 14 percent by Weight of copper.

References Cited in the file of this patent UNITED STATES PATENTS 1,365,894 Day Jan. 18, 1921 1,771,350 Ramage July 22, 1930 1,784,215 Zi-ser Dec. 9, 1930 2,189,850 Whitner Feb. 13, 1940 2,673,145 Chandler Mar. 23, 1954 FOREIGN PATENTS France Apr. 15, 1903 OTHER REFERENCES and 

1. THE METHOD OF INHIBITING CORROSION IN METALLIC PETROLEUM DISTILLATION APPARATUS WHICH COMPRISE ADMIXING AN AMMONICAL COPPER CARBONATE COMPLEX WITH THE PETROLEUM BEING DISTILLED IN SAID APPARATUS
 11. A CHEMICAL COMPOSITION FOR INHIBITING CORRISION OF METALLIC PETROLEUM REFINING APPARATUS PROCESSED IN CONSTITUENTS CONTAINED IN THE PETROLEUM PROCESSED IN SAID APPARATUS, CONSISTING OF AN AQUEOUS SOLUTION OF AMMONICAL COPPER CARBONATE COMPLEX AND SODIUM CARBONATE. 